Separator and method of making the same



Patented July 8, 1924.

UNITED STATES PATENT OFFICE.

RAYMOND C. BENNER, OF BAYS-IDE, NEW YORK, ASSIGNOB, BY MESNE ASIGNMENTB,

TO THE PREST-O-LITE COMPANY, INC NEW YORK.

OF NEW YORK, N. Y., A CORPORATION 01' SEPARATOR AND METHOD OF MAKING THE SAME.

Io Drawing.

To all whom it may concern:

Be it known that I, RAYMOND C. BENNER, a citizen of the United States, residin at Bayside, in the county of Queens and tate 5 of New York, have invented certain new and useful Im rovements in Separators and Methods of Klaking the Same, of which the following is a specification.

'This invention relates to an improved storage battery separator and methods of maln'ng the same.

Thin sheets-of wood, now generally employed in the manufacture of storage battery separators are usually treated to free the wood of detrimental substances and have been impregnated with various materials to make them less subject to deterioration before service, and more durable in service.

However, wooden separators have certain distinct advantages, for example their lightness and the low resistance they ofi'er to the current in the battery but, in their natural condition and even after treament, they vary considerably in de ee of porosity, in

2 strength, in impurities which may be injurious in the operation of the battery, frequently warp and split because of the grain therein, and are also rather expensive, especially if they are selected to obtain uniform hi h quality separators.

The 0 ject of this invention is to provide an improved separator that is light and ofl'ers a low resistance to current, but is of uniform strength, uniformly porous, rigid acid-resistant, less expensive than wood, an free from deleterious substances.

Relatively cheap fibrous materials, desirably those which have been chemically treated and are entirely freed from substances which are or may be detrimental in the battery, are used as the raw materials for making the body of the improved separator. examples of such materials. Sulfite pulp, as is well known, is made from wood in large quantities as a raw material for the papermalcing industr and is therefore readily obtainable on t e market conditioned for use in separators having the deleterious substances such as resins gums and acetic acid forming agents already removed therefrom. Cotton linters are likewise readily obtainable as raw material, either chemically Sulfite pulp and cotton linters are,

Application filed May 2, 1922. Serial No. 557,906.

treated or not, as desired. The sulfite pulp, as well as the cotton linters, principally consist of relatively long fibers which may be loosely felted into sheets of the desired thickness and porosity by well known methods, and accordingly a separator that is uniform as to its strength, porosity and freedom from detrimental constituents may readily be obtained by properly controlling the fabrication of such sheets.

In order that the sheet orv body offibrous material shall have the requisite rigidity for service, as in a storage battery separator, suitable bonding and reinforcing material is incorporated either in the chemically treated fibrous material before it is formed into the sheet or into the sheet after it has been formed of such fibrous material.

For example, non-conductive acid-resistant plastic bonding agents such as rubber, celluloid and asphalt may be mixed with fibrous material such as sulfite pulp, after 7 which the mixture is fabricated into sheets, as desired. The rubber or celluloid is dissolved in an appropriate solvent, such as benzol or acetone, to provide a fluid plastic solution with which the fibrous material may be mixed. The mixture may be felted, pressed or otherwise formed into sheets of the desired thickness and the solvent then evaporated, which leaves the sheets rigid and pervious to a predetermined degree, with the fibers bonded together. The amount of bonding material eniployed depends upon the nature of the fibrous material used and upon the rigidity required. When cotton linters are used, sufficient plastic composition may be used to coat the fibers to protect them from attack by the electrolyte, whereas in the treatment of sulfite pulp a smaller amount of the composition will usually suf- Vfice to bond the fibers and provide the re quired rigidity for a separator.

Bituminous material rendered fluid by heating, such as asphalt, may also beemployed as a bonding and reinforcing agent to be incorporated with the fibrous material 1 before or after the formation of the sheet.

A jelly-forming substance, such as sodium silicate, may also be employed by itself as a bonding and reinforcing agent in the manner described, or may be combined with the 1 rubber, celluloid or bitumen. The sodium 1 These/separators may therefore be assemsilicate in the separator when acted upon by the electrolyte of the battery becomes gelatinous silicic acid, bonding, the loosely felted fibers together and filling the pores between them. This bonding agent thus prevents creepage of active material and growths through the separator but, being permeable to electrolytic action, permits free difilusion of the electrolyte and passage of electric current through the separator. The felted body of fibers has tortuous through passages or pores uniformly distributed throughout its area, and the rubber, celluloid and similar bonding material is so incorporated as not to obstruct these ores. The cementiti'ous material employed constitutes the sole means, aside from the felted arrangement of the lengthy fibers, for bonding these fibers to ether, since the treated fibrous material used is initially free from the natural gums, resins, etc. a

' On the other hand, sheets may first be formed from ap ropriate acid-resistant fibrous material and then impregnated with an acid-resistant plastic bonding agent, such as rubber or celluloid dissolved in an appropriate solvent. The solvent is then evaporated, which sets the bonding material and leaves the sheet porous to the desired de es. The sheet may also be treated with so 'um silicate, as already described.

The rubber bonding material may be vul-' canized in the separators by treating such rubber-bonded separators with a solution of sulfur monochlorid in'an appropriate solvent such as carbon bisulfide, drying the separators, washing them first in sodium bicarbonate solution and then with water, and finally drying them. The sheets of fibrous material may be treated initially with rubber and sulfur or other suitable vulcanizing a ent in an appropriate solvent, such as car on bisulfide. the solvent, the separator is heated to about 140 C. for from 2 to 5 hours to vulcanize the rubber.

The improved separators, made from bonded chemically treated but uncalendered fibrous materials such as sulfite pulp and cotton linters, possess the advantages of the best wooden and other separators in lightness, thinness and about the same low resistance to current in the battery. But they are much superior to such separators because they are less expensive, are more uniform in porosity and freedom from detrimental substances and fillers such as those used in papers, and having no grain, are of the same strength in all directions. To effectively reduce splitting and warping, wooden separators must be kept moistened, whereas the characteristics of the improved separator herein disclosed do not change even when kept in dry condition indefinitely.

After evaporating condition in batteries and shipped at s expense and inconvenience, and stored without danger of deterioration.

I claim 1. A storage battery separator consisting of a uniformly pervious sheet formed of fibers uniformly free from substances which detrimentally affect the operation of a battery, such sheet having cementitious material incorporated therein bonding said fibers together. 2. A storage battery separator comprising fibers felted into a sheet and bonded to gether solely by acid-resistant material, such sheet being rigid, of uniform strength in all directions, uniformly pervious t0 electrolyte, and uniforml free from substances that detrimentally a ect'the operation of a battery.

3. A storage battery separator consistin of a sheet formed of sulfite pulp fibers bon ed together and uniformly free from substances detrimental in the operation of a battery.

4. A storage battery separator consistin of a rigid uniformly ervious sheet formed of felted sulfite pulp hers bonded together by acid-resistant material and uniformly free from substances detrimentally afiecting the operation of a battery.

5. A storage battery separator according to claim 2, in which such bonding materia is vulcanized but does not obstruct the pores of said sheet.

6. A storage battery separator according to claim 2, in which the pores of such sheet bled in dry contain a jelly-forming substance permeable to electrolytic action.

7. A storage battery separator consisting of rigid porous sheet comprising cotton linters bonded together by acid-resistant material.

8. A method of making storage battery"- separators that comprises incorporating an acid-resistant bonding agent in a body of fibers free from substances detrimental in the operation of a battery, and forming such material into sheets adapted for use as separators.

9. A method of making storage battery separators that comprises the step of in- I corporating bonding material in a body of fibers that have been subjected to treatment uniformly freeing them of substances detrimentally aifecting the operation of a bat- 10. A method of making storage battery separators that comprises mixing acid-re: sistant lastic material with a body of fibers freed rom substances detrimental in the operation of a battery, and forming such mixture into sheets.

11. A method of making storage battery separators that comprises incorporating fluid bonding composition in a body of fibers I freed from substances detrimental in the operation of a battery, and solidifying such bonding composition.

12. A method of making storage battery separators that comprises incorporating fiuid bonding composition containing a volatile solvent in a body of fibers uniformly free from substances detrimental in the operation of a battery, and evaporating such solvent. 7

13. A method of making storage battery separators that comprises incorporating acid-resistant bonding material in a body of sulfite pulp fibers, and forming the same into separator sheets.

14. A method of making storage battery separators that comprises incorporatin vulcanizable bonding material in a ho y of fibers, forming the same info sheets, and vulcanizing such bonding material.

15. A method of making storage batteryseparators that comprises incorporating bonding material and jelly-forming material in a body of fibers uniformly freed from substances that detrimentally alfect the 25 operation of a battery.

In testimony whereof, I aflix my signature. 1

RAYMOND G. BENNERQ 

